Abstract
Purpose: :
To compare the optic nerve axonal architecture assessed with diffusion-tensor magnetic resonance (DT-MR) imaging, with morphological data of the optic nerve head and the retinal nerve fiber layer (RNFL) obtained with HRT-III, GDx Vcc and Stratus OCT.
Methods: :
Thirty six patients were examined: 24 were affected by primary open angle glaucoma (POAG) at different stages and 12 were normal subjects matched in age and sex. DT-MR imaging was performed with a 3-T MR unit and Mean Diffusivity (mMD) and Fractional Anisotropy (mFA) values were calculated for each optic nerve. The following clinical indexes were obtained from the three ophthalmological instruments. GDx Vcc: NFI, and meTSNIT. HRT-III: Disc Area, LCDR, RNFLt, Rim Area, Rim Volume, CSM, HVC, RB. OCT: avThickn. Their correlation with mMD and mFA were investigate by Pearson correlation matrix and by several multiple regression analysis.
Results: :
The highest correlation was found between mMD and LCDR (r=0.662), followed by avThickn (r=-.644), and NFI (r=0.642), and between mFA and LCDR (r=-0.499), RimArea (r=-0.445), and NFI and RB (r=0.433). mMD correlated with: LCDR (p=0.02), considering all variables; avThickness (p < 0.01), considering retinal fiber layer parameters; NFI (p<0.01), considering GDx parameters; avThickn (p< 0.01), considering OCT parameters; LCDR (p = 0.01), considering HRT-III morphometric parameters; RB (p = 0.02), considering HRT-III indexes. mFA correlated with: avThickn (p=0.02), considering OCT parameters; RB (p=0.01), considering HRT-III indexes.
Conclusions: :
Our study documents a significant correlation between axonal architecture of the optic nerves captured with DTi technology and morphological parameters obtained with GDx Vcc, HRT-III and OCT. This data suggest that DTi parameters can represent novel biomarkers of glaucoma severity and progression and may represent an adjunctive tool to asses neuroprotective properties of novel compounds.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • optic nerve • nerve fiber layer